I like the hair curl.
Usually when you make pixel art, you start off with a sketch and work of that, then you end up getting the best results. It's a choice you can make, but it really helps to get the anatomy straight, wich I find a bit lacking in your art: female shapes are a bit smoother then what you made in the picture (I'm talking about the hip area here people, no hormones involved), right now it looks more like a man to me (it seems more roughly shaped at least, IMO), no offense. It could also be the character position you work from, but then I sadly cannot deny the feeling that I find myself putting some question marks on the pose as well.
I'm not particulary sure what you consider finished and what not, but there is a huge amount of contrast in the hair area- whilst the curl is done pretty swell, I find the rest of the hair to be lacking a bit in shade and detaling, and that takes away the attention from the well-done curl, wich is a shame.
I don't like the expression at all, it doesn't remind me of Kiki (or well, the Kiki I know) in any form or shape. This is just a personal opinion, it seems like you were trying to stylise it that way. And needless to say art goes wasted on the barbarians like me.
Overall I'm not too font of the hat overall, it seems rather.. tacked on. The part were it should be firmly wrapped around the head I instead find details that would depict the very opposite- it losely lays on her gentle blue hair and when I look at it intensively, I end up finding the head shape a bit weird. Personally I'd redo the hat to resemble more or a french barret (probably misspelled, excuses in advantage), and then redo the Butterfree features on the hat.
Overall, I liked your other hi-res sprites better, mainly the BlazBlue ones (I think it was the Jin piece that I really liked). Considering your art skills, I strongly suggest you give the draw-scan-sprite technique a go. I have a really advanced tutorial that you could learn a lot from, would you be willing to expand your horizon. I have it waiting for you.